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Commit b6c7cfa

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Restore proper linkage of pg_char_to_encoding() and friends.
Back in the 8.3 era we discovered that it was problematic if libpq.so had encoding ID assignments different from the backend, which is possible because on some platforms libpq.so might be of a different major version from the calling programs. psql should use libpq's assignments, but initdb has to use the backend's, else it will put wrong values into pg_database. The solution devised in commit 8468146 relied on giving initdb its own copy of encnames.c rather than relying on the functions exported by libpq. Later, that metamorphosed into ensuring that libpgcommon got linked before libpq -- which made things OK for initdb but broke psql. We didn't notice for lack of any changes in enum pg_enc since then. Commit 06843df reversed that, fixing the latent bug in psql but adding one in initdb. The meson build infrastructure is also not being sufficiently careful about link order, and trying to make it so would be equally fragile. Hence, let's use a new scheme based on giving the libpq-exported symbols different real names than the same functions exported from libpgcommon.a or libpgcommon_srv.a. (We could distinguish those two cases as well, but there seems no need to.) libpq gets the official names to avoid an ABI break for libpq clients, while the other cases use #define's to make the real names "xxx_private" rather than "xxx". By controlling where the #define's are applied, we can force any particular client program to use one set or the other of the encnames.c functions. We cannot back-patch this, since it'd be an ABI break for backend loadable modules, but there seems little need to. We're just trying to ensure that the world is safe for hypothetical future additions to enum pg_enc. In passing this should fix "duplicate symbol" linker warnings that we've been seeing on AIX buildfarm members since commit 06843df. It's not very clear why that linker is complaining now, when there were strictly *more* duplicates visible before, but in any case this should remove the reason for complaint. Patch by me; thanks to Andres Freund for review. Discussion: https://postgr.es/m/2385119.1696354473@sss.pgh.pa.us
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‎src/bin/initdb/Makefile

Copy file name to clipboardExpand all lines: src/bin/initdb/Makefile
+4-5Lines changed: 4 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -16,13 +16,12 @@ subdir = src/bin/initdb
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top_builddir = ../../..
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include $(top_builddir)/src/Makefile.global
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override CPPFLAGS := -I$(libpq_srcdir) -I$(top_srcdir)/src/timezone $(ICU_CFLAGS) $(CPPFLAGS)
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# Note: it's important that we link to encnames.o from libpgcommon, not
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# from libpq, else we have risks of version skew if we run with a libpq
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# shared library from a different PG version. The libpq_pgport macro
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# should ensure that that happens.
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#
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# shared library from a different PG version. Define
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# USE_PRIVATE_ENCODING_FUNCS to ensure that that happens.
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override CPPFLAGS := -DUSE_PRIVATE_ENCODING_FUNCS -I$(libpq_srcdir) -I$(top_srcdir)/src/timezone $(ICU_CFLAGS) $(CPPFLAGS)
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# We need libpq only because fe_utils does.
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LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(ICU_LIBS)
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‎src/bin/initdb/meson.build

Copy file name to clipboardExpand all lines: src/bin/initdb/meson.build
+5-2Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,8 +7,6 @@ initdb_sources = files(
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initdb_sources += timezone_localtime_source
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#fixme: reimplement libpq_pgport logic
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if host_system == 'windows'
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initdb_sources += rc_bin_gen.process(win32ver_rc, extra_args: [
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'--NAME', 'initdb',
@@ -18,6 +16,11 @@ endif
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initdb = executable('initdb',
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initdb_sources,
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include_directories: [timezone_inc],
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# Note: it's important that we link to encnames.o from libpgcommon, not
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# from libpq, else we have risks of version skew if we run with a libpq
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# shared library from a different PG version. Define
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# USE_PRIVATE_ENCODING_FUNCS to ensure that that happens.
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c_args: ['-DUSE_PRIVATE_ENCODING_FUNCS'],
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dependencies: [frontend_code, libpq, icu, icu_i18n],
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kwargs: default_bin_args,
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)

‎src/common/Makefile

Copy file name to clipboardExpand all lines: src/common/Makefile
+7Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -140,6 +140,13 @@ libpgcommon.a: $(OBJS_FRONTEND)
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rm -f $@
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$(AR) $(AROPT) $@ $^
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#
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# Files in libpgcommon.a should use/export the "xxx_private" versions
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# of pg_char_to_encoding() and friends.
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#
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$(OBJS_FRONTEND): CPPFLAGS += -DUSE_PRIVATE_ENCODING_FUNCS
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#
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# Shared library versions of object files
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#

‎src/common/meson.build

Copy file name to clipboardExpand all lines: src/common/meson.build
+5-2Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -112,8 +112,8 @@ common_sources_frontend_static += files(
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'logging.c',
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)
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# Build pgport once for backend, once for use in frontend binaries, and once
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# for use in shared libraries
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# Build pgcommon once for backend, once for use in frontend binaries, and
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# once for use in shared libraries
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#
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# XXX: in most environments we could probably link_whole pgcommon_shlib
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# against pgcommon_static, instead of compiling twice.
@@ -131,6 +131,9 @@ pgcommon_variants = {
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'': default_lib_args + {
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'sources': common_sources_frontend_static,
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'dependencies': [frontend_common_code],
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# Files in libpgcommon.a should use/export the "xxx_private" versions
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# of pg_char_to_encoding() and friends.
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'c_args': ['-DUSE_PRIVATE_ENCODING_FUNCS'],
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},
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'_shlib': default_lib_args + {
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'pic': true,

‎src/include/mb/pg_wchar.h

Copy file name to clipboardExpand all lines: src/include/mb/pg_wchar.h
+20Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -13,6 +13,9 @@
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* included by libpq client programs. In particular, a libpq client
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* should not assume that the encoding IDs used by the version of libpq
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* it's linked to match up with the IDs declared here.
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* To help prevent mistakes, relevant functions that are exported by
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* libpq have a physically different name when being referenced
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* statically.
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*
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*-------------------------------------------------------------------------
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*/
@@ -562,6 +565,23 @@ surrogate_pair_to_codepoint(pg_wchar first, pg_wchar second)
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}
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/*
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* The functions in this list are exported by libpq, and we need to be sure
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* that we know which calls are satisfied by libpq and which are satisfied
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* by static linkage to libpgcommon. (This is because we might be using a
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* libpq.so that's of a different major version and has encoding IDs that
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* differ from the current version's.) The nominal function names are what
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* are actually used in and exported by libpq, while the names exported by
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* libpgcommon.a and libpgcommon_srv.a end in "_private".
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*/
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#if defined(USE_PRIVATE_ENCODING_FUNCS) || !defined(FRONTEND)
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#define pg_char_to_encoding pg_char_to_encoding_private
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#define pg_encoding_to_char pg_encoding_to_char_private
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#define pg_valid_server_encoding pg_valid_server_encoding_private
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#define pg_valid_server_encoding_id pg_valid_server_encoding_id_private
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#define pg_utf_mblen pg_utf_mblen_private
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#endif
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/*
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* These functions are considered part of libpq's exported API and
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* are also declared in libpq-fe.h.

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